The present invention relates to a printing apparatus and a printing method, and more particularly, to a reduction in a printing time with respect to a printing apparatus for printing by using a printhead having an array of printing elements and a printing method for the printing apparatus.
As an information output device for a word processor, a personal computer, a facsimile machine and the like, a printer, which performs printing based on information of desired characters and images, on a sheet-type print medium such as a print sheet or a film, is known.
As a printing method of the printer, various methods are known. In recent years, attention has been especially paid to an ink-jet method because of its capability of printing without contact with a print sheet, low running cost, readiness of color printing and quiet printing by a non-impact method.
Further, among ink-jet printing apparatuses, a full-line type printing apparatus, having a printhead having arrayed printing elements (nozzles) corresponding to the width of maximum printing area of print medium, for performing printing while transferring the print medium, has become widely used because printing at higher speed is possible.
In color printing by this full-line type printing apparatus, reduction in printing speed is prevented by arranging the plural printheads to discharge ink of different colors in a transfer direction of the print medium for simultaneous ink discharge from the respective printheads.
As the full-line type printhead (long head) has several thousands of ink discharge nozzles, the nozzles are divided into several blocks, and discharge control is performed by using the combination of two types of control signals.
FIG. 5 is a block diagram showing the construction of a drive control circuit of the full-line type printhead in a case where discharge control is performed on 24 nozzles divided into six 4-nozzle blocks.
In FIG. 5, reference numeral 111 denotes a discharge control signal generation circuit common to all the nozzles; 112, a nozzle designation circuit to determine nozzles to discharge ink; 113, a nozzle designation decoder to designate a nozzle to be driven among the four nozzles of each block; 114, a block designation decoder to designate a block to be driven among the six blocks; 115, 3-input AND gates provided for the respective nozzles; and 116, discharge circuits for the respective nozzles.
Further, symbol ENB denotes a discharge control signal; NSEL (0-1), a binarized nozzle designation code signal to designate a nozzle to discharge ink in each block; NZL (1-4), a nozzle designation signal obtained by decoding the nozzle designation code signal by the nozzle designation decoder 113; BSEL (0-2), a binarized block designation code signal to designate a block to discharge ink; BLK (1-6), a block designation signal obtained by decoding the block designation code signal by the block designation decoder 114; and HEET (1-24), a discharge control signal for each nozzle.
FIG. 6 is a timing chart showing respective signal states when the first to twenty-fourth nozzles are sequentially driven. Symbol CNT denotes a signal from a counter in the nozzle designation circuit 112. When the counter value is xe2x80x9c0xe2x80x9d, the first nozzle is driven; when the counter value is xe2x80x9c1xe2x80x9d, the second nozzle is driven; and when the counter value is xe2x80x9c23xe2x80x9d, the twenty-fourth nozzle is driven.
In this manner, in accordance with change of the counter value from xe2x80x9c0xe2x80x9d to xe2x80x9c23xe2x80x9d, the signal states are changed as shown, to sequentially drive all the 24 nozzles from the first nozzle in synchronization with the counter value change.
FIG. 7 schematically shows a general structure of a printing apparatus having the full-line type printhead. The printing apparatus has a sheet feed section 2 to feed a print medium to a printing area, a transfer section 3 to transfer the print medium, a sheet discharge section 4 to discharge the print medium on which printing has been completed, and a full-line type printhead section 7 fixed in a vertical direction to a transfer direction.
As an operation upon printing, the sheet feed section 2 feeds a print medium P to the transfer section 3, then the transfer section 3 transfers the print medium P to pass the full-line type printhead section 7 while printing is performed. Since printing is performed in a fixed position, the length of the full-line type printhead section 7 is longer than that of the print medium P appropriate for printing by the printing apparatus in an orthogonal direction to the transfer direction (hereinafter xe2x80x9cprint medium widthxe2x80x9d).
As described above, the printing apparatus using the full-line type printhead, that performs printing while passing a print medium through the printing area of the fixed printhead, is appropriate for printing at higher speed than that of the so-called serial type printing apparatus which performs printing by repeating scanning of a printhead mounted on a carriage and transfer of the print medium.
However, in the conventional printing apparatus using the full-line type printhead, discharge control is performed at timing the same as that of discharge control in use of all the nozzles, regardless of print medium width and the width of actual printing area.
Actually, wasteful discharge control is performed on nozzles in positions where printing is not performed, which disturbs further reduction of printing period.
Further, with regard to nozzles which are not actually used, preliminary discharge (idle discharge) must be performed periodically. However, in the conventional apparatus, after printing for a predetermined amount, e.g., printing for one print sheet, preliminary discharge is performed on all the nozzles regardless of actual used/unused states of the nozzles.
Accordingly, the preliminary discharge consumes a large amount of ink, and takes much time. This especially influences continuous printing on plural print media.
The present invention has been made in consideration of the above situation, and can provide a printing apparatus and method for high-speed printing by performing drive control only on printing elements requiring drive control while omitting drive control on printing elements not requiring drive control.
This can be attained by a printing apparatus which performs printing by using a printhead having an array of printing elements, comprising: block selection means for dividing the array of printing elements into a plurality of blocks, each having a predetermined number of printing elements, and selecting blocks to be used for printing among the plural blocks; block designation means for designating from among the blocks selected by the block selection means; printing element designation means for designating a printing element to be driven in each of the designated blocks; and drive control means for driving respective printing elements by operating the printing element designation means only for the blocks selected by the block selection means.
Further, this can be attained by a printing method for performing printing by using a printhead having an array of printing elements, comprising: a block selection step of dividing the array of printing elements into plural blocks, each having a predetermined number of printing elements, and selecting blocks to be used for printing among the plural blocks; a block designation step of designating from among the blocks selected in the block selection step; a printing element designation step of designating a printing element to be driven in each of the designated blocks; and a drive control step of driving respective printing elements by performing the printing element designation step only for the blocks selected in the block selection step.
That is, according to the present invention as described above, for performing printing in accordance with input information by a printhead having an array of printing elements, the array of printing elements is divided into plural blocks, each having a predetermined number of printing elements, and blocks to be used for printing among the plural blocks are selected, blocks from among the selected blocks are designated, a printing element to be driven in each of the designated blocks is designated, and respective printing elements only in the selected blocks are driven.
By this arrangement, the drive control procedure on a block not actually driven can be omitted.
Further, in an ink-jet printing method or the like, in a case where preliminary discharge must be performed on printing elements (nozzles) not used in printing, the preliminary discharge can be performed only on printing elements which have not been actually used in printing. Thus the period of preliminary discharge can be reduced, and the period of printing can be reduced when printing is continuously performed.
Note that as the block designation, it is preferable that the block designation means designates a block within a range from a first block number to a second block number as a block to be actually driven, or the block designation means designates blocks within two ranges including a first block number and a second block number as blocks to be actually driven.
In this case, it is preferable that the block designation means has plural registers for storing a block number of the designated block.